"I'm extremely concerned, I mean this is yet another symptom, or another indication, of a criminal regime using criminal acts," ElBaradei, former head of the U.N. nuclear agency, said of the provocative charging of demonstrators by loyalists of embattled Egyptian President Hosni Mubarak. "My fear is that it will turn into a bloodbath."

ElBaradei said Mubarak's regime "does not want to listen to the people, does not want to understand that they need to go," adding that the president's insistence on staying in office through fall elections only strengthens the resolve of Egyptians that he must resign "immediately, before the country goes down the drain."

ElBaradei on Tuesday called Mubarak's tandem vows to complete his term but not seek reelection a "trick" geared to tamping down his opponents' passions, but one that was unlikely to succeed.

His forecast played out at dusk Wednesday when Mubarak supporters attacked anti-government demonstrators in Cairo's central Tahrir Square, provoking a melee of rock-throwing, firebombing and beatings. The army, which had urged demonstrators to go home after Mubarak's speech late Tuesday, turned water cannon on the protesters to disperse them and extinguish the fires ignited by Molotov cocktails.